I24, what 7AC said, and yes, the battery is scrap. You might get it to work a little with prolonged conditioning, but it will never give you satisfactory service again. A Cessna with the master on, and everything switched off, will draw between 2 and 4 amps, so you can do the math from the number of amp hours of the battery as to how long it will power the idle plane. Though perhaps possible to start and fly with a reconditioned junk battery, you're defeating the provisions which the airplane was designed to to fly for at least 30 minutes with electrical power (which you'd like to have at landing for flaps) following an alternator failure. Alternators fail, as do drive belts (which you have), and I've had to fly home on the battery a few times. Best to invest in the new battery.